The rate of human invention is faster, and the rate of cultural loss is slower, in areas occupied by many competing societies with many individuals and in contact with societies elsewhere.

Perhaps our greatest distinction as a species is our capacity, unique among animals, to make counter-evolutionary choices.

Eurasia ended up with the most domesticated animal species in part because it's the world's largest land mass and offered the most wild species to begin with.

History as well as life itself is complicated -- neither life nor history is an enterprise for those who seek simplicity and consistency.

Rhino-mounted Bantu shock troops could have overthrown the Roman Empire. It never happened.

A blueprint for disaster in any society is when the elite are capable of insulating themselves.

I decided that now is the time to start doing the things that really interest me and I find important. It was in the 10 years of the MacArthur grant that I began working on my first book... and I began putting more work into environmental history.